Resonances in Nuclei, Atoms, and Molecules: Why are They so Interesting?

Processes that are otherwise unlikely become quite probable near resonances. This high probability allows one to probe features of few-body interactions that might be inaccessible otherwise. This review will highlight studies relevant to few-body species that exploit unique properties of resonances. The examples that are discussed show some of the potential of experimental techniques, such as atom trapping, new generation light sources, and storage rings that have been perfected in the last few years. The theoretical background for these studies is outlined so as to highlight what the central features.